Cars arrive at an oil change center following a Poisson process at the rate of four per hour. There is a single available mechanic, and the time taken to perform an oil change is exponentially distributed, with an average of 12 minutes.
Steady-state distribution for the system.
Distribution for the number of cars in the system.
Probability that there are more than three cars at the oil change center.
Mean and variance for the number of cars in the system.